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Re: home made wind tunnel(weight/frontal)

To: dad land <eaglemot@bellsouth.net>,
Subject: Re: home made wind tunnel(weight/frontal)
From: Twin Jugs Cycle <twinjugsharley@yahoo.com>
Date: Fri, 24 Jan 2003 08:59:44 -0800 (PST)
Good question John on the down force
measurement(lift). You know dad... concerning lift I
thought of something I had accidently tried when John
wrote that.
I used a scale to weigh my bike like normal and had
applied a little "pressure rearward to the front of
the bike" simuluating acceleration(i was looking more
at the frontal area changing then what I'm getting at
here though). It's amazing how much weight transfer
there is on the back and the same thing on weight
transfer to the front tire when "pulling" on the front
trying to simulate gear changes. 
 Was thinking how "2" bathroom scales might work, 1
"under" the front tire and one "under" the rear tire.
It would give you static weight and then with
windspeed could give you an idea of the lift going
on(be it positive or negative), and also show weight
transfer front to rear or vice versa. Although I think
some of the rear to front is only going to happen on
the track during acceleration and between shifts.
Thoughts on that? 
I considered using another scale on the front to see
how much pressure I was applying but thought it was
pretty irrelevant since it doesn't reflect the
aero-drag during a run - this  might be able to be a
little more accurate with a rope and pole hooked to
the front of the bike in the tunnel, if these figures
matter to you? 
What started me looking at it was thinking about how
the frontal area is slightly larger during
acceleration and a bit smaller during deceleration or
between shifts(I just happened to have my bike on the
scale when I did it- dumb luck that made my mind
wander further then it should have as it's created
another obsticle I want to overcome). I was simply
guessing the softer suspension one has, the more the
frontal area would be effected compared to a rigid.
But am now also thinking that weight transfer would
also be more effected on a hardtail then a rear
suspension setup? 

Todd Dross
Twin Jugs Racing
#1300b

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